Title: Thrombosis and Hemostasis Centers Research and Prevention Network Background: Venous thromboembolism and thrombophilia are common. However, (a) many of the mechanisms predisposing individuals, particularly those of black race, are not known, (b) health care delivery to these patients in the U.S. is often highly variable and (c) public awareness of these disorders and their seriousness is low. Objectives: To create a Comprehensive Thrombosis Clinic structure that (a) allows epidemiologic research to be done through use of a clinic patient registry, (b) enables the addition of a biologic sample repository to allow basic research questions to be asked off the Registry, (c) uses the Registry as an identification point of eligible patients for prospective studies on thrombosis and thrombophilia, (d) creates patient support group structures within North Carolina and (e) educates the public, patients and health care providers about thrombosis. Specific Aims: Aim #1: Support and expand the existing research capacity of the UNC Thrombophilia Program to allow collaborative epidemiological research on thrombosis and thrombophilia to be done;Aim #2: Engage in prospective, epidemiologic studies of the established patient cohort;Aim #3: Provide patient and provider education by working closely with regional and national organizations. Methods: In a collaborative effort with 7 other funded thrombophilia centers demographic and clinic data on outpatients and inpatients with thrombosis and/or thrombophilia will be entered into a Registry. These data will be used for collaborative epidemiologic studies. The principal investigator of this grant application will focus on the study of patients with (a) rare clotting disorders (compound thrombophilias), and (b) uncommon blood clots (abdominal venous thromboses). Retrospective studies on the former and latter, and a prospective study of the latter patient population during pregnancy are proposed. The Registry data will also be evaluated for differences in referral patterns of patients of black compared to people of white race, and differences in the type of thrombosis they have had. The biologic sample repository will serve as a resource to study yet unknown risk factors of blood clots in people of black race. Finally, a mechanism is suggested to create patient support groups throughout N.C. and to improve the education of the public and of health care providers through structured seminars. Close collaboration with national non-profit patient and health care provider organizations are suggested to maximize the success of these efforts.